Textile filament having apparent variable denier



J. G. SIMS June 23, 1964 TEXTILE FILAMENT HAVING APPARENT VARIABLE DENIER Filed Nov. .21, 1962 FIG. I.

INVENTOR. J G SIMS FIG.3.

ATTORNEY United States Patent 3,138,516 TEXTILE FILAMENT HAVING APPARENT VARIABLE DENIER James G. Sims, Pensacola, Fla, assignor to Monsanto Company, a corporation of Delaware Filed Nov. 21, 1962, Ser. No. 239,189 3 Claims. (CL 161-179) The present invention relates to a novelty textile fila ment having an appearance resembling a variable denier filament together with the method and apparatus for producing the filament. More particularly, the novel filament according to the presnt invention has a substantially constant cross-sectional area but has a crosssectional configuration which varies along its length.

Variable denier yarns made according to the prior art presented several problems in processing the filaments into yarns and the yarns into fabrics. Such prior art filaments were typically produced by variably drawing the filaments, thus producing portions of the filaments which had been considerably stretched and leaving other portions substantially unstreched. The large portions occasionally would catch in a restricted area, such as the eye of a needle. Furthermore, the differences in physical properties resulting from the variable drawing produced undesirable non-uniform physical properties in the filaments. Such prior art filaments usually had to be further treated to provide high-contrast variable dye receptivity.

Accordingly, it is an object of the invention to provide a constant denier filament having an apparent variable denier and an actual variable covering power.

A further object is to provide a filament of the above character in which the cross-sectional shape varies although the cross-sectional area remains constant along the filament.

A further object is to facilitate provision of a selfcrimping filament wherein the crimping is random in kind and extent.

A further object is to provide a filament of the above character which possesses random receptivity to dyeing.

A further object is to provide a filament of the above character which imparts novel desirable handle, luster, and porosity to textile fabrics.

A further object is to provide a novel method and apparatus for producing filaments of the above character.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the several steps and the relation of one or more of said steps with respect to each of the others, and the article possessing the features, properties, and relation of elements which are exemplified in the following detailed disclosure and the scope of the invention will be indicated in the claims.

For a more complete understanding of the nature and objects of the invention, reference should be made to the following detailed description taken in connection with the drawing in which:

FIGURE 1 is an enlarged plan view of a fragment of a spinneret;

FIGURE 2 is a perspective view of a portion of a novel filament according to the present invention;

FIGURE 3 is a schematic cross-sectional view of particular apparatus for producing the novel filament of FIGURE 2;

FIGURE 4 is a sectional view taken along line 4-4 of FIGURE 3; and

FIGURE 5 is a sectional view taken along line 55 of FIGURE 3.

Referring now to FIGURE 1, a molten polymer after being extruded through a non-circular orifice such as shown at 22 becomes solidified to form a continuous filament. It has been found that the cross-sectional shape of the solidified filament formed after extrusion through a given non-circular orifice is controlled primarily by the shear viscosity and the dynamic surface tension of the extruding melt. Within the constraints of the system, surface tension acts to reduce the surface free energy to a minimum, corresponding to a circular cross-section; conversely, viscous forces resist flow within the molten filament. Hence, a filament of high viscosity polymer tends to retain the general cross-sectional configuration of the non-circular orifice, but a low viscosity molten filament tends to become circular before solidification.

The above considerations permit the formation of a novel filament having a substantially constant denier but a variable cross section. Upon extruding a noncircular stream composed of macroscopically discrete polymer components differing widely in their respective ratios of viscosity to surface tension, a filament is produced having a variable cross-sectional shape along the length of the filament, as illustrated in FIGURE 2. As shown therein, the filament 24 has an upper portion 26 which is substantially cruciform in shape, corresponding approximately to the shape of the spinneret orifice 22. The lower portion 28 of filament 24 has a substantially circular cross-sectional shape and is considerably smaller in diameter than the apparent width of portion 26, indicated in the circurnscribing dotted projection at 30, although the cross-sectional areas of portions 26 and 28 are the same.

Such a filament configuration has many applications as a novelty filament when the appearance of a variable denier or extended slub is desired. The variations in apparent thickness impart greater natural bulk to the filament and provide for substantial inter-filament friction. Since the filament actually has an approximately constant denier throughout its length, its physical strength is substantially uniform. The filament may be readily drawn on conventional drawing equipment with only minor modifications without the likelihood of excessive breakage or other problems in handling.

An exemplary apparatus for producing the novel filament shown in FIGURE 2 is illustrated in FIGURES 3-5.

Referring to FIGURE 3, the spinneret block 20 includes a channel 32 communicating with the inlet of conventional constant-volume metering pump 33. A small channel 37 delivers polymer from the outlet of metering pump 33 to the back side of spinneret 18 from whence the polymer extrudes through non-circular orifice 22. A pair of tubular polymer supply channels 34 and 36 extend downwardly through block 20 and are alternately connected to channel 32 by a metering mechanism 38. The metering mechanism 38, in the exemplary form illustrated, includes a shaft 40 extending through and rotatably journaled in block 20, intersecting channels 34 and 36. A metering passage 42 extends through shaft 40 in alignment with channel 34, and connects this channel to channel 32 when shaft 40 is properly oriented. A similar metering passage 44 is provided in shaft 40 for connecting channel 36 to channel 32 when channel 34 is not so connected. The axes of passages 42 and 44 are arranged at right angles to one another when viewed parallel to the axis of rod 40. Means is provided for rotating shaft 40, such as the illustrated gear 46, which may be driven by a motor, for example.

In the position illustrated in FIGURE 3, channel 34 is connected to channel 32 by passage 42, while channel 36 is isolated from chamber 32 due to the relative orientation of passages 42 and 44. Upon rotation of 3 shaft 40 approximately 90, this situation will be reversed and the polymer in channel 36 will then be supplied through passage 44 to channel 32 for delivery to the inlet of metering pump 33. At intermediate positions of rotation, both channel 34 and channel 36 are connected to channel 32 but to differing extents, providing a supply of polymer at all times to metering pump 33. The entire spinning block assembly is surrounded by a heating jacket (not shown) to control temperature at the level required for proper flowing of the molten polymers.

To form the novel textured filament of FIGURE 2, polymers having substantially differing ratios of viscosity to surface tension at the spinning temperature are supplied under pressure to channels 34 and 36 by suitable pumping equipment (not shown). The polymers should be compatible; i.e., they should be miscible so that a strong bond forms between the components. Thus, the polymer in channel 34 may have a relatively high ratio of viscosity to surface tension as compared to the polymer in channel 36.

Metering shaft 40 is rotated, either at a constant or variable angular velocity, to alternately supply polymer to channel 32 from channel 34 and from channel 36. Thus the stream extruded from orifice 22 will have portions composed primarily or entirely of the polymer from channel 34, and portions composed primarily or entirely of polymer from channel 36, together with intermediate or transition regions as shown at 48 having a composition across the section including polymer components from both supply channels.

The stream thus extruded is cooled and solidified at an appropriate rate such that the polymer components from channel 34 tend to retain the shape of orifice 22 (see portion 26 in FIGURE 2), while the components from channel 36 tend to coalesce into a circular crosssection. The cooling may, for example, be provided by a stream of air directed onto the extruded polymer stream.

If necessary, various other means may be employed to ensure extrusion of a constant total volume of polymer in a given time. Thus, different pump pressures may be used for the polymers in channels 34 and 36, or metering passages 42 and 44 may have different cross sections in order to compensate for differences in polymer viscosities.

If polymers are chosen that differ not only in the ratio of viscosity to surface tension, but also in the latent degree of shrinkage under the influence of heat or moisture, a self-crimping yarn results. Self-crimping yarns have been produced heretofore by conjugate spinning under conditions which yield filaments of substantially constant cross-sectional shape. The present method of spinning through non-circular orifices provides distinct advantages over the conventional method, however, because the filament cross-sectional shape varies continually, and more importantly, the transitions from one polymer component to the other are predominantly axially asymmetrical as illustrated at 48 in FIGURE 2. Therefore, the usual uniform helical crimp does not develop. Instead, the crimp is random both in kind and In extent: helical crimp may extend a few inches followed by saw-toothed convolutions that vary randomly in amplitude, period, and in axial plane. Bulk and interfilament cohesion of such self-crimping yarns will exceed that of conventional conjugate spun round filament yarns.

Another useful variation is to choose polymers which differ not only in the ratio of viscosity to the surface tension, but in dye receptivity as well. For example, the polymers extruded may be a low viscosity stream of nylon 6 and a high viscosity stream of nylon 66. If these are extruded through a non-circular orifice, the nylon 6 will, in general, dye darker than the nylon 66 resulting in yarn with novel irregular streaks along the filaments; or nylon 66 polymer containing deep-dye additives may be combined with normal nylon 66 polymer. A similar variation would be to extrude streams of meltcolored polymers; e.g., one polymer stream colored with blue pigment may be combined with another which is colored white or is uncolored. The resultant yarn exhibits an attractive variegated blue and white coloration when it is converted into fabric.

As has been set forth above, the novel method makes possible the production of a filament having an appearance resembling a variable denier although the denier actually remains substantially constant along its length. The use of polymer components which differ in their latent degree of shrinkage under the influence of heat or moisture provides a self-crimping filament wherein the crimping is random in kind and extent. The combination of polymer components which vary in dye receptivity provides novel filaments having a desirable random variegated coloration. The filaments produced according to the present invention possess a novel desirable hand, luster and porosity when incorporated into a fabric and possess a substantial amount of inter-filament friction.

It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained and, since certain changes may be made in carrying out the above method and in the article set forth without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all state ments of the scope of the invention which, as a matter of language, might be said to fall therebetween.

Having described my invention, what I claim as new and desire to secure by Letters Patent is:

l. A textured continuous filament of substantially constant denier comprising:

(a) a substantially constant cross-sectional throughout a major portion of its length, and

(b) a cross-sectional configuration which repetitively varies along said portion from a substantially circular configuration to a substantially non-circular configuration.

2. A textured continuous self-crimping filament of substantially constant denier comprising:

(a) a plurality of portions of varying length connected by transition regions;

(b) alternate portions along the length of said filament having differing latent degrees of contraction and blending into one another in said transition regions asymmetrically with respect to the axis of said filament.

3. The combination of claim 2 wherein said alternate portions have different cross-sectional shapes and substantially the same cross-sectional area.

area

References Cited in the file of this patent UNITED STATES PATENTS 2,434,533 Wurzburger Jan. 13, 1948 2,866,256 Matlin Dec. 30, 1958 2,953,427 Egger Sept. 20, 1960 3,012,846 Froitzheim et a1. Dec. 12, 1961 

1. A TEXTURED CONTINUOUS FILAMENT OF SUBSTANTIALLY CONSTANT DENIER COMPRISING: (A) A SUBSTANTIALLY CONSTANT CROSS-SECTIONAL AREA THROUGHOUT A MAJOR PORTION OF ITS LENGTH, AND (B) A CROSS-SECTIONAL CONFIGURATION WHICH REPETITIVELY VARIES ALONG SAID PORTION FROM A SUBSTANTIALLY CIRCULAR CONFIGURATION TO A SUBSTANTIALLY NON-CIRCULAR CONFIGURATION. 